中文摘要：

采用上下桶分根法研究了3年生沙打旺的根系提水作用及土壤水势与植物组织水势、植物渗透调节物质之间的关系。结果表明，当上下桶土壤体积含水量和水势分别在14．9％和-1．28MPa、19％和-0．6MPa左右时，下桶土壤水势〉下桶根水势〉上桶根水势〉上桶土壤水势〉叶水势，出现沙打旺根系提水现象。上桶土壤含水量和土壤水势的日变化在晴天表现为：7：00～16：00急剧下降，16：00～22：00上升较快并于22：00达到最大值，之后缓慢下降；而其在阴天随时间的推移呈现缓慢下降趋势。沙打旺叶片中K^＋、可溶性糖和脯氨酸含量等渗透调节物质在16：00和22：00均高于根中，16：00上桶根和叶片中脯氨酸、可溶性糖、K^＋和Na^＋的含量显著高于22：00，由此产生了上桶根水势、叶水势的日变化，促进了沙打旺的提水作用。

英文摘要：

The experiment studied hydraulic lift of Astragalus adsurgens Pall. planted for three years by u- sing the split-root apparatus. We investigated the relationships between the hydraulic lift and the soil water potential,the water potential of plant tissues and the osmotic adjusting materials. The results showed that when the soil volumetric water content and the soil water potential in upper pot reached 14.9% and -1.28 MPa,and in lower pot reached 19 M and -0.6 MPa respectively. The soil water potential in lower pot〉the root water potential in lower pot〉the root water potential in upper pot〉the soil water potential in upper pot〉the leaf water potential. At the same time, the phenomenon of hydraulic lift would occur. In sunny days,the soil volumetric water content and the soil water potential in upper pot declined from 7 AM to 16 PM and increased from 16 PM to 22 PM,reached maximum at 22 PM,and declined subsequently. In cloudy days,the soil volumetric water content and the soil water potential in upper pot declined gradually. The concentrations of the osmotic adjusting materials（including proline, soluble sugar, K＋ and Na~） in the leaves and the roots in upper pot at 16 PM were higher than that at 22 PM,which could result in the varia- tions of leaf water potential and root water potential in upper pot to some extent,and finally promoted the occurrence of hydraulic lift of A. adsurgens.